Engine components such as a block or transmission are generally die cast components that are machined on an assembly line to have various shapes, bores, and through-holes formed therein. Because the components are generally die cast, the components may have porosities. After the components are machined and finished, these porosities may be opened or connected to create larger. This is disadvantageous because the engine components are generally filtered with oil or some other lubricant that assists in lubricating the various moving parts of the completed engine or transmission. Accordingly, it is common to test the engine component for any oil leaks that may be present due to manufacturing tolerances or, more importantly, due to open porosities that may have been formed during machining.
One such oil test is generally known as a cold test. During a cold test, the engine component is placed in an oil testing device and pressurized air is injected into the component. Then, the decay rate of pressurized a leaving the component is measured to determine whether any leaks are present in the component. If the decay rate is too high, the component is discarded due to the presence of a leak that may cause the engine component to fail when the component is placed in a motor vehicle.
A cold test, however, has a disadvantage in that the engine component is tested at temperatures that are less than an operating temperature (i.e., a temperature that the component will reach during use in a motor vehicle). In other words, the engine component undergoes thermal expansion at operating temperatures which may cause any porosities that may be present in the engine component to expand. This expansion of the porosities may cause the development of oil leaks that may otherwise go undetected when the engine component is being tested for leaks during a cold test.